1978 CB750 Wiring Diagram: A Comprehensive Guide

When it comes to restoring a classic motorcycle like the 1978 Honda CB750, having a reliable wiring diagram is essential. Not only does it ensure that your bike runs smoothly, but it also ensures your safety on the road. However, finding a quality wiring diagram can be challenging, especially for an older bike like the CB750.

Why Do You Need a Wiring Diagram for Your CB750?

The Honda CB750 was first introduced in 1969 and quickly became one of the most popular motorcycles of its time. It was known for its reliability, power, and speed, and it quickly gained a cult following among motorcycle enthusiasts.

However, over time, the wiring system on the CB750 can become corroded, damaged, or frayed, which can lead to electrical problems. Without a reliable wiring diagram, it can be challenging to diagnose and fix these issues.

What Are the Electrical Components of a CB750?

Before we dive into the wiring diagram for the CB750, let’s take a quick look at the electrical components that make up the bike’s wiring system:

Component Description
Battery The power source for the CB750’s electrical system
Rectifier Converts AC power from the engine into DC power for the battery
Starter motor Uses electrical power to crank the engine
Ignition coil Converts the battery’s DC power into high-voltage current for the spark plugs
Spark plugs Ignites the fuel mixture in the engine’s combustion chamber

Where Can You Find a Wiring Diagram for a 1978 CB750?

There are several resources for finding a wiring diagram for your CB750, including:

1. Honda Service Manual

The official Honda Service Manual for the CB750 includes a detailed wiring diagram, along with step-by-step instructions for maintaining and repairing the bike. You can usually find a digital copy of the service manual online or purchase a physical copy from a Honda dealership or online retailer.

2. Online Forums and Communities

There are several online forums and communities dedicated to vintage Honda motorcycles, including the CB750. These forums are a great place to connect with other enthusiasts and find advice, tips, and resources for restoring and maintaining your bike. Many of these forums also have wiring diagrams and other technical resources available for free.

3. Third-Party Service Manuals

There are several third-party service manuals available for the CB750, including Haynes and Clymer. These manuals are often less expensive than the official Honda Service Manual, and they may include additional information and resources.

Understanding the 1978 CB750 Wiring Diagram

Now that you have a reliable wiring diagram for your CB750, it’s essential to understand how to read and interpret it. Here are a few key tips:

1. Identify the Components

The first step is to identify the different electrical components on your CB750 and locate them on the wiring diagram. This will help you understand how the various components are connected and what their function is in the bike’s electrical system.

2. Follow the Wires

Next, follow the wires on the wiring diagram to see how they connect the various components. The wiring diagram will show you which wires are hot, which are ground, and which are connected to the different electrical components.

3. Understand the Symbols

Wiring diagrams use a variety of symbols to represent electrical components and connections. Make sure you understand what each symbol means before attempting to read the diagram.


1. Are Wiring Diagrams for the CB750 Easy to Find?

While finding a reliable wiring diagram for a vintage motorcycle like the CB750 can be challenging, there are several resources available. The official Honda Service Manual is the most reliable source, but online forums and third-party service manuals can also be helpful.

2. Can I Use a Wiring Diagram for a Different Year CB750?

While there are some similarities between the wiring systems on different years of the CB750, it’s always best to use a wiring diagram that’s specific to your bike’s year and model. Using the wrong wiring diagram can lead to electrical problems and safety hazards.

3. What Should I Do if I Can’t Find a Reliable Wiring Diagram?

If you’re having trouble finding a reliable wiring diagram for your CB750, try reaching out to other vintage motorcycle enthusiasts on online forums and communities. You may also want to consider hiring a professional mechanic who specializes in vintage Honda motorcycles.


A reliable wiring diagram is an essential tool for restoring and maintaining a classic motorcycle like the 1978 Honda CB750. With the right wiring diagram and a basic understanding of how to read it, you can diagnose and fix electrical issues on your bike and ensure that it runs safely and smoothly on the road.